In this paper we consider legal reasoning as a species of practical reasoning. As such it is important both that arguments are considered in the context of competing, attacking and supporting arguments, and that the possibility of rational disagreement is accommodated. We present two formal frameworks for considering systems of arguments: the standard framework of Dung, and an extension which relates arguments to values allowing for rational disagreement. We apply these frameworks to modelling a body of case law, explain how the frameworks can be generated to reconstruct legal reasoning in particular cases, and describe some tools to support the extraction of the value related knowledge required from a set of precedent cases.